public class Node{
    public int value;
    public Node left;
    public Node right;
    public Node(int data){
        this.value=data;
    }
}

public Node reConstructBT(int[] pre, int[] in){
    if(pre==null||in==null||pre.length!=in.length){
        return null;
    }

    return construct(pre,0,pre.length-1,in,0,in,length-1);
}


private Node construct 




